The short answer
When an American Standard furnace lights, runs a few seconds and shuts off, the flame sensor is the usual cause. In Northern Virginia it tends to show up on the first cold nights of fall. Newer American Standard furnaces, like the Silver S9X1 and Gold S9X2, show E08 on the door display as an early warning that the flame signal is weak, then E2.2 once the flame has dropped out ten times and the furnace has locked itself out for an hour. Older boards blink 8 for a weak flame or 2 for a lockout. A cleaning and a meter reading by a tech fixes most of them in one visit.
E08 is the warning, E2.2 is the lockout
The board watches the flame signal the whole time the burners are on. E08 means the signal is weak but the furnace is still running, and that’s almost always a dirty flame sensor. It’s your chance to book before it quits. E2.2 means the board lit the burners, lost the flame, and did that ten times in one call for heat, so it stopped for an hour. E08 for a week, then E2.2 on a cold morning, is the classic flame sensor story. Both come from the manufacturer’s S-series furnace manual, which American Standard shares with Trane.
Swipe to see all columns →
Swipe to see all columns →
| Code | What it means |
|---|---|
| E08 | Flame signal weak but still running, usually a dirty flame sensor |
| E2.2 | Flame lit, then was lost, ten times; locks out for an hour |
| E2.1 | No flame after three tries to light; locks out for an hour |
| 8 blinks | Older boards: weak flame signal |
| 2 blinks | Older boards: locked out, it never lit or kept dropping the flame |
E2.1 is a different story: three tries and the board never saw a flame. That’s more often the igniter or the gas supply, though a very dirty sensor can do it too, because the board can’t tell a flame it can’t read from no flame at all.
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How it looks from the basement
- The inducer starts, the igniter glows and the burners light.
- The flame burns a few seconds and goes out, and the inducer keeps running a little while.
- It tries again, and again. After ten losses the display flips to E2.2 and the house cools for an hour.
If the burners never light at all, it isn’t the sensor. Look at E3.2 and E2.1 in our American Standard furnace code guide, or the pressure switch guide.
What you can try
Set the thermostat to off. Turn off the breaker or the switch for the equipment, wait about five minutes, turn it back on and set the thermostat back. Do it once. That clears the hour-long lockout. Before you call, read the fault history: on the display models, press Menu until L6F shows, then press Option, and write down the last six codes. A string of E08s before the E2.2 tells the tech exactly what they’re walking into.
Leave the sensor itself to a tech. Getting to it means the burner area with gas and power just shut off, the ceramic base cracks easily, and the wrong abrasive leaves a film that reads worse than the dirt did.
What a tech does
The tech reads the code history, then shuts off power and gas and takes the sensor out, usually one screw. It’s cleaned with a fine pad, checked for cracks in the ceramic, put back with the rod sitting in the flame, and tested with a meter in microamps while the burners run. If it doesn’t read after cleaning, it’s replaced. Then the questions that keep it from coming back: is the flame even and blue, is the ground good, is the filter seated so dust isn’t blowing past it?
Why it keeps coming back
A sensor that’s dirty again in a few weeks is a sign, not bad luck. The usual reasons are a filter that doesn’t seal so dust gets into the burners, a burner that isn’t lined up with the rod, a weak ground wire, or combustion air pulled from a dusty or laundry area. A yearly check catches the slow buildup. Our heating check is $67 per system, through December 31: furnace, heat pump or boiler.
More American Standard and furnace guides
Every furnace code: American Standard furnace codes. Thermostat and heat pump alerts: American Standard error codes. The same board on a Trane: Trane 2 flashes. The same part on other brands: York flame sensor and the flame sensor problems guide. A furnace that runs a while and then stops is short cycling, a different problem. Every brand is in our error codes and warning lights guide, and our American Standard repair page has what we fix and what it costs.
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Book an American Standard repair
Call (703) 997-9757 or book online. A diagnostic visit is $99, and the tech reads the code, finds the part that set it and gives you the price before any work starts. We answer day or night. Our heating check is $67 per system, through December 31: furnace, heat pump or boiler. If someone already quoted you a new system, our free second opinion looks at it first. Rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276.
Questions people ask
What does E08 mean on an American Standard furnace?
The flame signal is weak but the furnace is still running. It’s an early warning, almost always a dirty flame sensor, and if nothing’s done it usually turns into an E2.2 lockout.
What does E2.2 mean on an American Standard furnace?
The flame lit and was lost ten times in one call for heat, so the furnace locked out for an hour. A power cycle clears it; a cleaned or new flame sensor keeps it from coming back.
Can I clean my American Standard flame sensor myself?
We’d leave it to a tech. The ceramic cracks easily, the wrong abrasive leaves a film, and a tech checks the reading with a meter afterward so you know it’s actually fixed.
Is the flame sensor code the same on Trane and American Standard?
Yes. The S-series furnaces share the same board and codes, so E08 and E2.2 mean the same thing on both.
